In celestial mechanics, the argument of latitude ( u {\displaystyle u} ) is an angular parameter that defines the position of a body moving along a Kepler orbit. It is the angle between the ascending node and the body.
It is the sum of the more commonly used true anomaly and argument of periapsis.
u = ν + ω {\displaystyle u=\nu +\omega } where u {\displaystyle u} is the argument of latitude, ν {\displaystyle \nu } the true anomaly, and ω {\displaystyle \omega } the argument of periapsis.
References Wakker, K. F. (2007). "Astrodynamics", Delft University of Technology.